You night not be up on cockney slang but there are few in this country i would be willing to wager that don't know the Rosie lee reference. You may not care but your child certainly will . Don't be selfish

Would you actually call her Rosie on a day to day basis, rather than the full Rosie Lea? If so then you could maybe call her Rosalind Lea in full for official forms etc, to get away from the 'nice cuppa Rosie Lee' connotations, but she'd be known as Rosie.